ceekack
Mechanical
- May 7, 2021
- 4
Hi, first time poster, frequent user of the site for the insight provided when it comes to GD&T.
I've run into something slightly unorthodox with one of our customers' Prints. I've attached a snippet of a mocked-up Part drawing that replicates what I am seeing on our Customer's Print. A couple simplifications have been made: 1) I didn't mark any casting datums on the Drawing, but they do exist on the Customer Print in question, so I included the note that references them as it may be relevant to the discussion. 2) I removed a large number of irrelevant notes for clarity.
The Customer calls out True Position on a few hole patterns relative to various Datums on the part via the DRF, but the hole locations in the table are all relative to a single hole (in the case of the supplied mock-up, hole "B2"). The way that I see this is that we should be pulling the Basics from hole to Datum from the CAD model; further, the hole locations shown on the Print seem to be purely for reference.
Am I thinking about this correctly?
As a little more background, this particular Customer doesn't call a relevant GD&T Standard (ASME, ISO, etc.) on any of their drawings, but they seem to follow (for the most part) ASME Y14.5M-2009, based off of their drafting practices and discussions I've had with their Engineers. The particular practice used here is replicated across a number of their new Prints and will likely prove confusing to the Operators on the Floor when they receive CMM readouts with nominals that don't match the Print. Talking with the CMM programmer, he's talking about making a bunch of secondary alignments to get the nominals to match what's being shown on the Print, which seems like a huge amount of work to fix something that our Customer made unintentionally confusing.
Hoping for some clarity and thanks for your help.
I've run into something slightly unorthodox with one of our customers' Prints. I've attached a snippet of a mocked-up Part drawing that replicates what I am seeing on our Customer's Print. A couple simplifications have been made: 1) I didn't mark any casting datums on the Drawing, but they do exist on the Customer Print in question, so I included the note that references them as it may be relevant to the discussion. 2) I removed a large number of irrelevant notes for clarity.
The Customer calls out True Position on a few hole patterns relative to various Datums on the part via the DRF, but the hole locations in the table are all relative to a single hole (in the case of the supplied mock-up, hole "B2"). The way that I see this is that we should be pulling the Basics from hole to Datum from the CAD model; further, the hole locations shown on the Print seem to be purely for reference.
Am I thinking about this correctly?
As a little more background, this particular Customer doesn't call a relevant GD&T Standard (ASME, ISO, etc.) on any of their drawings, but they seem to follow (for the most part) ASME Y14.5M-2009, based off of their drafting practices and discussions I've had with their Engineers. The particular practice used here is replicated across a number of their new Prints and will likely prove confusing to the Operators on the Floor when they receive CMM readouts with nominals that don't match the Print. Talking with the CMM programmer, he's talking about making a bunch of secondary alignments to get the nominals to match what's being shown on the Print, which seems like a huge amount of work to fix something that our Customer made unintentionally confusing.
Hoping for some clarity and thanks for your help.